1. Field of the Invention
The present invention relates to an intraocular lens insertion tool used to insert an intraocular lens into the eye.
2. Description of the Related Art
One method employed in the past in the field of cataract surgery involves extracting the intracapsular crystalline lens through a surgical incision made in ocular tissue such as the cornea (sclera) or anterior capsule section of the crystalline lens, and once the crystalline lens has been removed, inserting an intraocular lens serving as a replacement for the crystalline lens back through the incision and positioning it within the capsule.
Particularly in recent years, methods that employ an intraocular lens insertion tool like that disclosed in Japanese Patent No. 3412103 or Japanese Patent No. 3420724 have come into widespread use. Typically, the intraocular lens will be inserted into the eye by first inserting the distal orifice of an insertion tube provided at the distal end section of the body of the tool through a surgical incision, then pushing the intraocular lens (which has been maintained in a state of compact deformation inside the body of the tool) out through the distal orifice of the insertion tube. By employing such an insertion tool, the intraocular lens can be inserted into the eye without expanding the surgical incision that was made for the purpose of extracting the crystalline lens, thereby reducing the labor entailed in the surgical operation, as well as reducing the risk of post-surgical astigmatism or infection.
Such a surgical operation to insert an intraocular lens into the eye of the patient requires reliability and rapidity. Therefore, a burden on the patient will be reduced and a risk of infection will be restrained.
In light of this objective, one important procedure during surgery is to visually check that the intraocular lens has been set at the prescribed location within the intraocular lens insertion tool being used, just prior to the surgical operation to insert the intraocular lens into the eye of the patient using the intraocular lens insertion tool. Additionally, in some cases it will be necessary to check that the intraocular lens that has been positioned in the intraocular lens insertion tool is not folded; or to check the position or shape of the haptics of the intraocular lens. Such visual inspection will be necessary both in cases where the intraocular lens is provided in a separate package from the intraocular lens insertion tool, and the intraocular lens must be positioned in the insertion tool prior to surgery; and in cases where the intraocular lens insertion tool is provided with intraocular lens already accommodated inside.
In order to make such visual inspection it would be conceivable to provide a recloseable cover at the site where the intraocular lens is positioned within the tool body of the intraocular lens insertion tool, and to perform visual inspection by opening and reclosing the cover. However, this requires a very tedious operation to open and reclose the cover, and is impractical due to the considerable wasted time and effort. Moreover, there is a risk that during the cover opening and reclosing operation, the tool body of the intraocular lens insertion tool will be subjected to shock, causing problems such as deformation or displacement of the intraocular lens that is housed inside.
Accordingly, it has been contemplated to fabricate the intraocular lens setting location of the tool body of the intraocular lens insertion tool of light-transmissive synthetic resin or similar material, so as to permit a visual examination of the intraocular lens to be made through the peripheral wall of the tool body once positioned inside.
However, since the intraocular lens itself is also transmissive of visible light, it will be necessary to make the peripheral wall of the tool body sufficiently thin so that the intraocular lens inside will be visible through the peripheral wall of the tool body. Thus, an associated problem is the difficulty of ensuring the component strength required of the tool body.
In order to address this problem, one conceivable approach would be for the tool body of the intraocular lens insertion tool to have as separate structures a section adapted to house the intraocular lens positioned therein, and a nozzle section situated at the distal end side thereof and adapted to guide the intraocular lens into the eye. By making the nozzle section a separate structure, it will be possible for the nozzle section only to be imparted with high strength; and by assembling this section together with the intraocular lens housing section, for the thin housing section to be reinforced by the nozzle section.
However, it is undesirable for the tool body to have such an assembled structure of several parts, not only due to the complexity of manufacture entailed by the increased number of parts but also to the risk that the intraocular lens insertion tool will be defective due to improper assembly.